The power consumption of an air-cooled case can be suppressed through performing natural cooling by stopping a cooling fan in a case of low heat generation and performing forced cooling by driving the cooling fan in a case of high heat generation. In that case, the cooling capacity is lost unless the flow of cooling air is set to be suited for each of the cases of natural cooling and forced cooling. The air-cooled case depicted in Patent Document 1 is capable of setting the flow of cooling air either for the case of natural cooling or for the case of forced cooling by changing metal fittings.
In the meantime, Patent Document 2 discloses: an opening part formed on the side surface of a case; a louver which opens the opening part by its weight and closes the opening part by an air pressure from a cooling fan; and a louver which closes the opening part by its weight and opens the opening part by the air pressure from the cooling fan. Those louvers work to close the opening part for not producing a noise when it is unnecessary to let in the outside air.
Patent Document 3 discloses: Two opening parts formed on the side surfaces of a wind tunnel; and an evacuation movable plate and an aspiration movable plate for opening and closing each of those opening parts. Further, the evacuation movable plate automatically closes the opening part by a negative pressure at the time of operating a push-in fan, and the aspiration movable plate automatically closes the opening part by a negative pressure at the time of operating an intake fan. The evacuation movable plate and the aspiration movable plate have improved the reliability by generating a same flow of air in the wind tunnel both when operating the push-in fan and when operating the in-take fan so as to be able to deal with a case where one of the fans breaks down.
Patent Document 4 discloses an aspiration path opening/closing member which is provided on an aspiration path for opening/closing the aspiration path. The aspiration path opening/closing member is formed by a flexible film, which normally opens the aspiration path to let in the outside air and closes the aspiration path by an air pressure when operating an evacuation fan to suppress leak of the noise of the evacuation fan.    Patent Document 1: Japanese Unexamined Patent Publication 2000-277954 (Abstract)    Patent Document 2: Japanese Unexamined Patent Publication 2010-026381 (Paragraphs 0018, 0019, 0026, 0027, FIG. 2, FIG. 4)    Patent Document 3: Japanese Unexamined Patent Publication Hei 08-280106 (Paragraphs 0008 to 0011, FIG. 1, FIG. 2)    Patent Document 4: Japanese Unexamined Patent Publication Hei 10-161510 (Paragraph 0012 FIG. 5)
However, while the technique depicted in Patent Document 1 is capable of setting the flow of cooling air either for the case of natural cooling or for the case of forced cooling, it is extremely troublesome since the metal fittings need to be changed by hands.
Further, the techniques depicted in Patent Documents 2 to 4 are designed to reduce the noise or to improve the reliability. Thus, there are large differences in the techniques, and the issue in the technique depicted in Patent Document 1 cannot be overcome with those.
It is therefore an object of the present invention to provide an air-cooled case which is capable of automatically setting a flow of cooling air for each of the cases of natural cooling and forced cooling.